The following abbreviations and terms are herewith defined, at least some of which are referred to within the following description of the present disclosure.    3GPP 3rd-Generation Partnership Project    AGCH Access Grant Channel    ASIC Application Specific Integrated Circuit    BLER Block Error Rate    CDMA Code Division Multiple Access    CN Core Network    CRC Cyclic Redundancy Check    DL Downlink    DSP Digital Signal Processor    EDGE Enhanced Data rates for GSM Evolution    EGPRS Enhanced General Packet Radio Service    FCCH Frequency Correction Channel    GMSK Gaussian Minimum Shift Keying    GSM Global System for Mobile Communications    HARQ Hybrid Automatic Repeat Request    IoT Internet of Things    LTE Long-Term Evolution    M2M Machine-to-Machine    MCS Modulation and Coding Scheme    MS Mobile Station    MTC Machine-Type Communications    PCH Paging Channel    PLMN Public Land Mobile Network    RACH Random Access Channel    SCH Synchronization Channel    TDMA Time Division Multiple Access    TSC Training Sequence Code    UE User Equipment    UL Uplink    WCDMA Wideband Code Division Multiple Access    WiMAX Worldwide Interoperability for Microwave AccessCoverage Class: At any point in time a device belongs to a specific uplink/downlink coverage class which determines the total number of blind transmissions to be used when transmitting/receiving radio blocks. An uplink/downlink coverage class applicable at any point in time can differ between different logical channels. Upon initiating a system access a device determines the uplink/downlink coverage class applicable to the RACH/AGCH based on estimating the number of blind repetitions of a radio block needed by the BSS receiver/device receiver to experience a BLER (block error rate) of approximately 10%. The BSS determines the uplink/downlink coverage class to be used by a device on the device's assigned packet channel resources based on estimating the number of blind repetitions of a radio block needed to satisfy a target BLER and considering the number of HARQ retransmissions (of a radio block) that will, on average, result from using that target BLER.Extended Coverage: The general principle of extended coverage is that of using blind repetitions for the control channels and for the data channels. In addition, for the data channels the use of blind repetitions assuming MCS-1 (i.e., the lowest MCS supported in EGPRS today) is combined with HARQ retransmissions to realize the needed level of data transmission performance. Support for extended coverage is realized by defining different coverage classes. A different number of blind repetitions are associated with each of the coverage classes wherein extended coverage is associated with coverage classes for which multiple blind repetitions are needed (i.e., a single blind repetition is considered as the reference coverage). The number of total blind transmissions for a given coverage class can differ between different logical channels.Implicit Reject Status: This is a system access control mechanism used to prevent variable percentages of wireless devices from attempting system access according to the loading of the RACH. The wireless devices read the SCH prior to attempting system access and determine the value of the Implicit Reject Status (IRS) parameter therein to determine if system access using the RACH is allowed. This determination will, for example, be made based on the type of application layer payload that is available for transmission and whether or not that type of payload information is currently allowed according to the Implicit Reject Status parameter. Blocking the use of RACH for a variable percentage of wireless devices using IRS is realized by setting the IRS parameter to indicate a certain blocking condition for a percentage of SCH transmissions that reflects the target blocking rate (e.g., setting the IRS parameter to indicate a target blocking condition for 10% of the time will block about 10% of wireless devices subject to that blocking condition from using the RACH).
There are several ways in cellular systems today to control system access by a wireless device if there is congestion within the cellular system. One example is to use access class barring where the system includes a barring mask sent within the System Information to indicate the subset of wireless device access classes that are barred from accessing the system. Another example and more immediate (i.e., more real time) congestion control scheme which is supported in Global System for Mobile (GSM) systems and Enhanced Data Rates for GSM evolution (EDGE) systems is the implicit reject feature that mandates a wireless device to read an access grant channel (AGCH) or paging channel (PCH) in the downlink (DL) and look for the implicit reject flag (reference 3GPP TS 44.018 V12.2.0 (2014-03)—the contents of which are incorporated by reference herein). If the implicit reject flag is set and the wireless device is configured for low access priority, then the wireless device is not allowed to access the cellular system. The implicit reject flag is only relevant to wireless devices configured for low access priority and hence the behavior of higher priority wireless devices is transparent to the implicit reject indication.
When extending the coverage of the GSM/EDGE system to cater for wireless devices in radio coverage that is worse than what is typically supported by the cellular system, the use of repetitions is foreseen in which a specific block is repeated a number of times by the transmitter in order for the receiver to accumulate the repeated blocks and thereby be able to decode that specific block.
Although wireless devices in more diverse deployments can be reached by the use of repetitions, the drawback is that the system capacity can be greatly impacted due to the additional radio transmissions resulting from the repetitions (i.e., each repetition requires a distinct radio transmission).
Consider an example where it is determined that 16 repetitions (i.e., 16 transmissions) are needed to reach a 20 dB coverage improvement in the GSM/EDGE. In this example, the transmitting of the same information to two different wireless devices, in terms of radio resources utilized, could differ by a factor of 16. Unfortunately, the wireless devices configured for low access priority that are in deep coverage holes (requiring for example 16 repetitions) and that monitor the AGCH and PCH for the implicit reject flag, will not be able to decode a DL radio block after receiving a single transmission thereof and will therefore not be able to determine the implicit reject status information included therein. The net result of this is that, until these low priority access wireless devices can determine the implicit reject status, they will default to assuming the system access is barred and thereby experience a significant delay prior to attempting to access the cellular system (i.e., even when implicit reject status indicates system access is allowed).
One way of solving this problem is to, in every DL AGCH block or PCH block, send the blocks with the maximum number of repetitions (for example 16) needed to reach all of the wireless devices. However, this scheme will consume extensive radio resources in the cellular system and would require an over-dimensioning of the AGCH and/or PCH resources. This particular problem and other problems associated with the prior art are addressed in the present disclosure.